I don't know anything about them really. I don't drive my car all that much so a set of pads lasts forever.

The pads I have are a Performance Friction pad that Derrick Dong told me about when he was alive. The compound was not available for a Porsche big caliper in the front but was for some other manufacturers caliper for a "police special" application but it had a couple of spring clips I had to remove to drop them in. The rear pad was a perfect fit. I wish I knew what they were now since they really work nice, good bite, good fade resistance and not too much dust. The first time I got them really hot they smoked a LOT but only that one time. Maybe someone else has these and can weigh in.

 

Stock 993 uses 23.8mm TRW vacuum boosted m/c, It's a one off design for the 993 and there are no other m/c's w/ this design, which attaches at both ends


993RS/Cup/t usea a 25.4mm electro-hydraulic boost set up that would be very expensive and difficult to install on a vac. boost car.

There is however a 25.4mm TRW m/c that can be installed w/ a sort of crutch, the crutch is being made by a fellow named Konrad details here

the 23.8mm works fine w/ the Big red 993RS calipers for street use but for a performance application the 25.4 mm is much better, you get the slave/master ratio lower which improves modulation and feel I'd even go further and want a 27mm

 

If tracking the car I'd go w/ a 2 piece slotted rotor like Gyrodisk, I know the correct fronts are available and believe that the rears may also be availanow
fronts, the slotted hold up way better than the holey ones in track use, the rear doesn't see anywhere near the abuse as the fronts do so it's way less important there

rears w/ the same hours as the above fronts


I used the aluminum front RS backing plates


But there are other ways to go here too
Cupcars 964 Cup backing



w/ these the main goal is to shield the electrics(ABS sensors mostly) and rubber components

 

Good job...I see that you went for the RS calipers...curious how much more they cost these days vs. what I paid per the document in the earlier part of this thread i.e. have the tariffs changed things drastically or not?

I've also attached a pic of more icing on the cake for your front suspension and steering during your brake upgrade to wit the Rothsport red poly stiffer steering rack bushings seen in the attached picture (your old ones may disintegrate in your hands when you take them off if they're OE!) and the Tarett Engineering RSR-style inner tie rods shown earlier both items relatively inexpensive in the grand scheme of things! Please note that you're also going to need a lot of small parts per my earlier in the thread (actually Cupcar's) lists.

The attached undercarriage pic is a little disorienting but the front of the car is up. Note the retained vacuum brake assist and BTW, the pictured 5-way adjustable RS front sway bar is a PIA to get in but Cupcar finally had his way with it and I'm still not sure how he did it but we had to take part of the front suspension apart to get the OE M030 bar out and the RS bar in. Note how we've painted (per the factory) every bolt & nut that we set to factory torque specs. Also note the strengthening bar across the leading edge of the steering rack that the factory spec'd for strengthening purposes with 18" wheels (my car came with the M408 option Turbo Technology 18" hollow spokes).

Re: earlier issues in this thread per additional research in Porsche literature...the brake proportioning valve is the same 993 RS, C2S and C4S but the Turbo changeover point is higher which makes sense because of the greater rear weight bias. And "yes" no spacers are required to use the OE uprights with your brake mods.

And "yes" my car has been dry ice blasted because it was more than a bit of a mess when I got the car 2 years ago!

-Russ

 

base 993 uses 1 x40bar p/v that cuts rear line pressure by 46% above the 40 bar knee

cars w/ M220 option have 2x of the same p/v

993RS same as M220 option cars

993tt has 2 x55bar 46%, which reduce rear line pressure by 46% above the 55 bar knee

I've run both w/ and w/o the p/v's either works fine but w/ RS rear you do want to be sure to run the car low, stiffly sprung and w/ an effective lsd for best performance

 

Russ wrote: Good job...I see that you went for the RS calipers...curious how much more they cost these days vs. what I paid per the document in the earlier part of this thread i.e. have the tariffs changed things drastically or not?

R/e the RS calipers I found them here in the US @Sunset Porsche for $96 each more than you paid. I found on eBay a pair of new old stock Big Red Calipers in factory Porsche boxes for $132 less each than you paid. But since I have gone all OE Porsche on all the rotors you've blown me out of the water pricing wise.

Russ wrote: I've also attached a pic of more icing on the cake for your front suspension and steering during your brake upgrade to wit the Rothsport red poly stiffer steering rack bushings seen in the attached picture (your old ones may disintegrate in your hands when you take them off if they're OE!) and the Tarett Engineering RSR-style inner tie rods shown earlier both items relatively inexpensive in the grand scheme of things! Please note that you're also going to need a lot of small parts per my earlier in the thread (actually Cupcar's) lists.

Working on the fasteners, backing plates, wear sensors, don't know yet what brake pads and thinking about new brake lines from the tub to the calipers.

As far as all the suspension mods etc. I'm not going there, did that on a hot rod 914-6 that was so racy that the wifey would not even ride in the car. I'm putting the big brakes on because really just for the look... it matches up with my dream version of the car i've wanted for 29 years.

 

In the end do you track your car with or without the P/V?

The Carrera Cup and GT2 RSR used no P/V's and there is a line kit to eliminate them which I have installed.

I think to make the system pressure to pedal pressure response curve linear without a "knee", but who knows??

 

part of the problem w/ a p/v is the hysteresis it adds to the system, even w/o the p/v there is a input - response delay, a p/v makes it much worse



there is no doubt that a p/v that is ideally functioning would improve braking performance

 

Very cool stuff Bill-

Makes total sense since there is a P/V spring in a system which is not already stiff enough with caliper flexing too.

I bet that off pedal perturbation in line pressure is not welcomed by a good trail braking driver during corner entry. Hence the p/v elimination in the race cars.

I am sure I could never tell any difference since I can barely stop the car in a straight line at a stop light.

 

Here is a diagram showing the springs in a p/v valve, in this case with an adjustable pressure.

 

Brake caliper ****. Big Reds and RS calipers. Parts are coming in.... so excited. Hopefully on the car in about 10 days.

 

Presume you have new mounting bolts and the short hard lines on order?

Also, as an FYI, most people skip the brake pad "spiders". I opted not to install them during the conversion. Bill also doesn't run them. They seem to be more headache than their worth.

 

I don't run them either and don't notice noise that is objectionable.

The spiders are a PIA when replacing brake pads and I think they also may conduct unwanted heat into the caliper piston.

 

Can you educate me as to what you are referring to? Which numbered item are the parts you describe? Thanks

 

Parts 18 and 19 "damper plates"